WordPress.org

I want to encourage my users even more by adding a question or statement before the emoting options

This is possible using WordPress built-in custom fields. Add a field with the name emo-vote and choose value. The value can be unique for each post.

The buttons looks like crappy blue squares in Internet Explorer 6

How about upgrading your browser? Just kidding, some unlucky ones are still stuck with IE6. I would recommend TwinHelix's PNGFix. Place iepngfix.htc and blank.gif files in your webroot and add behavior: url(/iepngfix.htc); to the #input_0-#input_4 elements inside your emo-vote.css file.

I don't get any callback after emoting

Some might experience a lack of callback after emoting. In other words, the new values aren't sent back as they should. The callback is using the PHP function json_encode() to easily parse the callback with JavaScript. JSON was first introduced in PHP 5.2. Check your current installed version of PHP and ask your host kindly to upgrade if you're using an older version than 5.2.

The sidebar widget isn't up-to-date

The info shown in the widget is begin cached for 15 minutes to reduce the number of SQL-queries. So there's no need to panic.